1. Field of the Invention
The present invention relates to a manufacturing method of semiconductor devices and, more particularly, to a recognition method of a mark provided on a semiconductor wafer or chip and a manufacturing method and a mounting method of a semiconductor device using such a mark recognition method.
2. Description of the Related Art
Generally in a manufacturing process of semiconductor devices, it is necessary to perform position recognition of a semiconductor wafer or a semiconductor chip. Generally, a method of carrying out the image recognition of a recognition mark provided on a circuit pattern side of a semiconductor wafer or a semiconductor device is used for position recognition. That is, as shown in FIG. 1, a white light etc. is irradiated at the recognition mark (not shown) that has been formed simultaneously with a circuit pattern 2 of a semiconductor wafer 1 so as to monitor the reflection light by a visible-light camera 3 from the side of the circuit pattern surface and recognize the position of the recognition mark.
The FIG. 2 is an illustration showing a manufacturing process of a regular semiconductor device. In the manufacturing process shown in FIG. 2, first, a protective tape 4 is applied onto a circuit pattern surface 2 of a wafer 1, and a back surface 1a of the wafer 1 is grinded so as reduce a thickness of the wafer 1. For example, the thickness of the wafer before grinding is about 700 μm, and the grinding is carried out until the thickness becomes about 15 μm. A dicing tape 5 is applied onto the back surface 1a of the thinned wafer 1, and, subsequently, the protective tape 4 is removed. Thereby, the circuit pattern 2 and a recognition mark are exposed on to the surface, and the image recognition by the visible-light camera 3 becomes possible from the side of the circuit pattern.
Additionally, Japanese Laid-Open Patent Applications No. 6-244245 and No. 3-23646 disclose image recognition methods using an infrared light, which transmits through single-crystal silicon. According to this method, a light transmitted through the single-crystal silicon is limited to an infrared light so as to recognize a recognition mark existing on a circuit pattern surface by an infrared camera on the side of the back surface of a semiconductor chip. It is proposed to use such a method in face-down mounting such as flip-chip mounting or the like.
When the image recognition from the side of the circuit pattern surface is taken into consideration, it is always necessary to perform the tape replacing process to apply a dicing tape 5 and remove the protective tape 4 after reducing the thickness of the wafer 1 after grinding the back surface of the wafer 1. The tape replacing process needs a long production tact time, which causes an increase in cost.
Additionally, since a mechanical strength of the thin wafer falls remarkably, a wafer crack may occur in the tape replacing process. Furthermore, in the recognition on the side of the circuit pattern surface, there is a high possibility of occurrence of a recognition error due to a halation or an external noise.
On the other hand, when the recognition is made on the side of the back surface of the wafer by using transmission of an infrared light, it is very difficult to visually represent a difference in the characteristic since the most part of the infrared light is transmitted through even if the recognition mark and parts surrounding the recognition mark have different transmission characteristics with respect to an infrared since the thickness of the recognition mark and the surrounding parts (circuit patterns) are very thin. Therefore, there is a high-possibility that the contrast of the recognition mark and the surrounding parts become low, which results in a recognition error and is not practical. Additionally, a general-purpose visible-light source, a general-purpose camera, etc. cannot be used as an image recognition unit, but an expensive infrared light-source and an expensive infrared camera are needed.